1. Field of the Invention
The present invention relates to finish compositions for yarns and more particularly, to associative thickeners which enable the viscosity of the composition to be controlled as a function of the water content.
2. Description of the Prior Art
Spin finishes and process finishes are compositions normally employed in the fiber industry for lubrication of filaments or yarns during textile operations i.e., during the melt spinning, drawing, weaving or knitting or otherwise fabricating individual filaments or staple fibers into various textile articles. In addition to the essential lubricating agent and its solvent or emulsifying liquid, such as water, small amounts of other modifying agents may also be present. Generally, finishes comprise a lubricating oil, an antistatic agent, and an emulsifier.
The spin and process finish compositions are generally applied as dilute aqueous solutions having an oil base content by weight in the range of 1 to 30% and preferably 8 to 15%. The viscosity of the composition should be less than about 10 cps to ensure good spreading of the finish on the yarns.
A large number of spin and process finish compositions have been developed over the years. The composition of such finishes, of course, depends on the specific process requirements. Typically, a key consideration in formulating suitable compositions is the viscosity of the oil component of the finish since such was observed to influence the number of broken filaments and the tackiness of the snow formed on the texturings disks. Thus, it has been observed that, in terms of optimizing the composition with respect to the snow formation, the viscosity of the initial oil-based composition ideally should be less than 60 cps at 45.degree. C., while a higher viscosity is needed at intermediate water contents during the processing.
Despite the careful controlling of the viscosity of the oil component or, at most, of the initial water/oil emulsion, the treated yarns have nonetheless not been completely satisfactory but rather, have often exhibited mediocre or poor package build characteristics and poor yarn bundle coherence properties.